How is Checking of an algorithm done ?

Checking of an algorithm: After deciding strategy or technique to solve problem and generate an algorithm. We first check that the algorithm is suitable for given problem i.e. in other words we check that the algorithm give desired result for the set of input. To check the algorithm with set of input we generally use techniques such as proof by contradiction, proof by direct method or direct proof, proof by contraposition, proof by counterexample, proofby mathematical induction. By using these techniques we check that algorithm provides correct solution or not. If not then make changes according to it.